Frederick Sinclair's true colors were shown during the TV series
Among the other named business oligarchs we see in attendance at the Vault-Tec meeting in the final episode of season 1, besides Robert House, is Frederick Sinclair. He's representing Big Mountain.
Those who played the Dead Money DLC for Fallout: New Vegas will recognize Sinclair, as he's the guy who constructed the Sierra Madre Resort & Casino at which the DLC's events take place.
However, some fans have felt that there's a discrepancy between how Sinclair is depicted here vs. the image of him we are given from reading terminal entries and looking at murals around the Sierra Madre.
For instance, Dead Money and Old World Blues have it stated that Sinclair is just a client of Big MT, whereas the TV series has him serving as Big MT's representative at this meeting.
Another point of contention is how Sinclair's physical appearance and personality in the TV show is very different from how it is depicted in Dead Money. In Dead Money, Sinclair is portrayed as a suave man of average weight with brown hair and a mustache (albeit only on pre-War murals), and has a much more youthful and regretful personality. But the TV series makes him older, portly, and very crass.
We have remarks made by Dead Money's project director Chris Avellone where he felt that Sinclair's physical appearance on-screen "didn't really mesh with his appearance in the Sierra Madre."
However, I'd argue that we're not seeing any retcons at all, and nothing about Sinclair's presence at the meeting contradicts what we learn about him from Dead Money. In fact, if anything, his presence in the show informs a lot of the backstory we learned in Dead Money.
Sinclair's foreknowledge:
One thing that is clearly noted from reading terminal entries and a few journal entries, is that Sinclair clearly believed that a nuclear war was imminent:
Now that we know he was at this meeting to collaborate with Vault-Tec, we understand why he felt this way: much like Mr. House, he had foreknowledge. That's why he built the Casino like a fortress. That's why he invested in technology like the Vending Machines, the holograms, and the Auto Docs.
Sinclair almost went broke in the process of procuring the Vending Machines and the holograms for the Sierra Madre. To compensate, he permitted Big MT to conduct some experiments in the Villa. One of the experiments that Big MT did at the Villa was put an airborne toxin in the Villa's shoddy ventilation system, and then pump it out to see what would happen. This put several construction workers out of commission due to the effects it had on them, and is ultimately the source of the Cloud. To deal with the problem, Sinclair negotiated with Big MT to procure hazmat suits for the workers to go in and try and find where the Cloud had originated from. Unbeknownst to Sinclair, the hazmat suits were intentionally designed poorly, such that the users were exposed to the Cloud and also found themselves getting trapped in the suits (and could only be freed by having someone else cut them out with a Cosmic knife). These two experiments combined are what led to the construction crew becoming the Ghost People who inhabit the Villa.
While terminal entries in Old World Blues suggest that Sinclair didn't know about the Cloud being a Big MT experiment, the TV show makes me think that actually, he DID know. When the executives begin tossing out ideas for vault experiments, listen to the second idea that Sinclair pitches: he proposes a vault where psychotropic drugs are pumped into the air supply (which was ultimately implemented in Vault 106 out in the Capital Wasteland). That's an experiment that's very similar to the Cloud experiment, which involved an airborne toxin being pumped out of a ventilation system. Perhaps Sinclair knew exactly what the Cloud was, and its true origins, and this discovery was still fresh in his mind at the time of the meeting with Vault-Tec.
Sinclair's relationship with Vera Keyes:
Sinclair's depiction as an old and crass businessman does change the nature of his relationship to Vera Keyes. If the Sierra Madre murals of Sinclair are taken at face value...
...he comes off like a middle aged man in love with someone close to him in age, who was very heartbroken by finding out she was an unwitting accomplice to Dean Domino's plans to rob from him.
But with his depiction in the show, his relationship with Vera looks a lot different. Instead of being this middle aged man pining for a woman close to him in age, he's an old man who's obsessed with a young starlet at least 40 years his junior (information on Vera suggests she was in her late 20s when the Gala Event took place, and Sinclair looks to be in his late 60s/early 70s).
Him being an old man also makes a lot of sense when one considers his relationship to Dean Domino. Dean Domino was probably in his early to mid-60s in 2077 (going off Barry Dennen's age at the time that Dead Money was being developed), so close in age to Sinclair. It makes it more believable that Sinclair would've readily trusted Dean regarding Vera and the Villa construction, and thus be blinded to the truth that Vera was Dean's accomplice in the scheme to rob the vault, and also not be aware that Dean was profiting from Mr. Yesterday's scheme to cheat Sinclair by intentionally constructing the Villa with subpar building materials.
There's also these lines from Dean's dialogue regarding Sinclair and Vera that make a lot more sense when you know Sinclair is an old man:
"Ghost in name and image. Still a looker, though. Got to hand it to Sinclair, sure can pick 'em. Well, or get picked. Whichever."
"Vera was a big star, back before the Bomb. Not the best actress, but… well, she had other talents. Nice voice, nice legs. For some reason, Sinclair... he built this place... she caught his eye. Once he was hooked, that was it, had to have her. So made the introductions, and guess what? He builds this place for her, like some kind of Cleopatra obsession. Wasn't always a deathtrap."
Courier: "Why did you need [Vera]?"
Dean: "Because she could get closer to Sinclair than I ever could. Sinclair was already puppy-eyed, so all I had to do was the introductions. She smiled, fluttered her eyes, showed a little leg ...and he built this whole place for her. Made her the key to his vault, like a joke, cause of her name. Her fake Hollywood name. Except Sinclair didn't know I'd been there first. I could twist her whatever direction I wanted."
With that age gap in mind, coupled with his foreknowledge of Vault-Tec's plans, it also makes a lot of sense why Sinclair would build the Casino like a fortress, as he came to value Vera more than anything else in his life. He probably viewed her as the one thing he didn't want to lose when the Great War broke out. It's also understandable why he'd be so devastated to learn about Vera's betrayal and turn the vault into a death trap for her and Dean, though eventually came to regret this (and ultimately died trying to undo the trap).
Regarding the discrepancy in Sinclair's involvement with Big Mountain, I think it's safe to say that he might've actually invested a lot of money into buying a controlling stake in Big MT in order to get them to install the Vending Machines, the holograms, the Auto Docs, and all the other technologies that went into the Sierra Madre. That's my explanation at least for why he'd be the person sent to represent Big MT when Vault-Tec reached out seeking to collaborate with them on the vault experiments.
My opinion as to why the murals depict Sinclair as a young man is because he's rather vain. He was pretty suave way back when, but whereas House has largely retained his good looks up until 2077, Sinclair is now old, balding and fat.
It's worth noting that Cooper Howard has an indirect connection to Sinclair and Dean Domino, as he once starred in a movie with Vera.
...and considering a number of Season 2 set leaks have established that we'll be seeing flashbacks of Las Vegas before the Great War, I think there's a strong chance we'll get to see Cooper interact with Vera and Dean. Dean was very much present in Las Vegas at the time, as evidenced by some of his dialogue and the pre-War posters of him that can be found on loading screens and at a few locations on the Strip in the main game. So maybe Cooper will get to interact with the two of them as they were before Vera died and Dean became a ghoul.
And if they canonize Dean surviving Dead Money (which happens if you didn't bruise his ego while recruiting him), maybe Lucy and Cooper will get to interact with him when they get to New Vegas as his ending slides suggest that that's where he goes after he leaves the Sierra Madre.
I think that Vault-Tec invited Big MT to the table because they also wanted access to the same technologies Sinclair was installing in the Sierra Madre. The Vending Machines and the Auto Docs are pieces of technology that would definitely be useful to have in a Vault, especially when the Vaults are supposed to be self-sustaining.
